Lubricating systems for sewing machines



Sept. 13, 1966 G. F. KELLER 3,272,164

LUBRICATING SYSTEMS FOR SEWING MACHINES Filed Feb. 12 1965 George F. Keller WITNESS.`

ATTORNEY.

United States Patent O 3,272,164 LUBRECATING SYSTEMS FOR SEWHNG MACHINES George F. Keller, Mountain Lakes, NJ., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Feb. 12, 1965, Ser. No. 432,223 3 Claims. (Cl. 112-256) This invention relates to lubricating systems for sewing machines and more particularly to a lubricating system for supplying oil to the raceway of a loop taker.

In sewing machines having a loop taker in which a rotary member rotates around a stationary member, lubricating the raceway between the rotary and stationary members has been a perennial problem. If too much oil is supplied to the raceway, oil will soil thread as it is manipulated `by the loop taker and spatter onto work material held just a fraction of an inch away on the worksupporting surface of the bed. If too little oil is supplied to the raceway, the parts will quickly wear out.

In addition, oil must be available to lubricate the `raceway the instant 4the sewing machine is started, for if the sewing machine is operated intermittently in a series of short sewing operations, as most sewing machines are, the sewing machine can be run all day without the raceway of the loop taker ever receiving a drop of oil.

It is, therefore, an object of this invention to provide an improved lubricating system for supplying just the right amount of oil to the raceway of a sewing machine loop taker.

Another object of the invention is to provide a lubricating system in accordance with the foregoing object in which oil is available to lubricate the raceway the instant the sewing machine is started.

The objects of the invention are accomplished by mounting a stationary capillary tube for oil in a hollow loop taker shaft. The stationary tube communicates with a conduit in the loop taker which transmits oil to the raceway. Oil is supplied to the stationary tube by means of an oil pump having an Archimedes screw. In series with the stationary tube and the oil pump is a manually adjustable needle valve.

The adjustable needle valve regulates the amount of oil supplied to the raceway of the loop taker. Oil is available to lubricate the raceway of the loop taker the instant the sewing machine is started because lthe small bore of the stationary capillary tube retains oil between sewing operations. In addition, oil can -be immediately pumped through the stationary tube without having to overcome centrifugal force as would be the case with a conduit which rotates with the loop taker shaft. Positioning the needle valve in series with the pump pressure permits faster response than the usual bypass control. The use of an oil pump having an Archimedes screw minimizes heat transfer to the oil. Heating of the oil is a characteristie of other type pumps, such as centrifugal pumps, which is `disadvantageous because changes in the temperature of oil are reflected by changes in viscosity and hence changes in the rate at which oil is delivered to the hook raceway.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIG. l is a cross-sectional view of a sewing machine bed, as viewed from the front of the machine, illustrating the lubricating system of the invention;

FIG. 2 is an enlarged cross-sectional view of the loop taker of FIG. 1; and

FIG. 3 is an enlarged cross-sectional view of the oil pump taken substantially along the line 3-3 in FIG. l.

With reference to the drawing, the invention is illustrated as embodied in a conventional sewing machine having a frame of which only a work-supporting bed 10 and a portion of a standard 11 are shown. A bracket arm (not shown) extends laterally from the top of the standard over the work-supporting bed. The bottom of the bed is closed by a drip pan 12 which contains an oil reservoir 13.

Mounted in the bed is a loop taker shaft 14. The loop taker shaft is journaled in a pair of lubricated bearings 15 and 16. Rotation is imparted to the loop taker shaft through a pair of bevel gears 17 and 18. One of the bevel gears 17 is connected to the standard-end of the loop taker shaft and the other bevel gear 18 is connected to a vertical shaft 19 in the standard. The vertical shaft in the `standard is driven by an arm shaft (not shown) extending longitudinally through the bracket arm. The arm shaft is in turn driven by an electric motor (not shown).

Connected to the other end of the loop taker shaft 14 is a loop taker, indicated generally at 20, of the type disclosed in the United States patent of Zonis, No. 2,417,403, granted March 1l, 1947. In general, the loop taker has a cup-shaped rotary member 21 and a stationary member 22. The rotary member is secured to the end of the loop taker shaft by a setscrew 23. The rotary member rotates around the stationary member which is restrained from roation by a connection (not shown) to the sewing machine frame.

Bearing surfaces are provided between the rotary and stationary members of the loop taker by a bearing rib 24 around the stationary member and an annular groove 25 in the cup-shaped rotary member. The annular groove constitutes a raceway 26 for the bearing rib on the stationary member. A portion of one side of the raceway is closed by a removable gib 27 on the rotary member. The removable gib provides the means for disassembly of the stationary member from the rotary member.

Formed in the rotary member of the loop taker is a conduit 28 which leads from a recess 29 at the end of the loop taker shaft to the raceway. An oil wick 30 is housed in the conduit, and a wall 31 seals off the recess 29 from the stationary member.

In accordance with this invention, an axial bore 32 is formed in the loop taker shaft 14. Threads 33 are formed at the loop taker-end of the bore to receive a screw portion 34 of a bearing tube 35 which is housed in the bore in the loop taker shaft. Slots 36 are formed in the head of the screw portion so that the bearing tube can be easily assembled and disassembled from the loop taker shaft.

The other end of the bore has an enlarged portion 37 to receive an outlet portion 38 of an oil pump, indicated generally at 39. The outlet portion has threads 40 to receive a screw portion 41 of a stationary capillary tube 42 which is disposed in an axial bore 43 in the bearing tube 35. The capillary tube, being cantilevered from the outlet portion of the oil pump, is supported against its own weight and the weight of oil held therein by the bearing tube. The bearing tube also reduces twisting forces imposed on the stationary capillary tube. The bore 32 in the loop taker shaft 14 could be made small enough to support the capillary tube. However, it is more economical to use a standard tube composed of a bearing material.

The oil pump includes a body portion 44 having a main bore 45 in which is journaled an Archimedes screw 46 on the end of the vertical shaft 19 in the standard. The Archimedes screw extends into the oil reservoir in the drip pan. A recess 47 leads from the main bore in which the Archimedes screw is journaled to a second bore 48 which communicates with the outlet portion 38 of the oil pump. Threads 49 are formed in the second bore to receive a needle valve 50. A spring 51 is cantilevered on the body portion by a screw 52 to bear against a knurled knob 53 on the needle valve to prevent the needle valve from turning as the machine vibrates during sewing operations.

To enable the oil pump to handle the pressurized lubricating requirements of the machine in addition to that of the rotary hook raceway, a manifold 54 is secured in a tapped recess 55 which communicates with the main bore 45 for the Archimedes screw 46. One oil line 56 leads from the manifold to the lubricated bearing at the loop taker-end of the loop taker shaft and another oil line 57 leads to a lubricating point (not shown) in the bracket arm.

In operation, when the sewing machine is started, oil is lifted by the Archimedes screw 46 from the oil reservoir 13 in the drip pan. The oil is deposited in the recess 47 off the main bore 45 and travels through the second bore 48 past the needle valve 50 into the outlet portion 38 of the oil pump. The oil travels from the outlet portion of the oil pump through the stationary capillary tube 42 and into the recess 29 at the end of the loop taker shaft where the oil is confined by the wall 31. Aided by centrifugal force, the oil then travels from the recess 29 at the end of the loop taker shaft through the wick 30 in the conduit 28 to the raceway 26 of the loop taker.

When the machine is stopped, oil is retained in the stationary capillary tube 42 because of its small bore. Thus, when the machine is again started, oil is instantly available to lubricate the raceway 26 of the loop taker. Constant oil pressure can be attained immediately because the oil does not have to overcome centrifugal force as would be the case with an oil tube which rotates with the loop taker shaft. Since the needle valve 50 is in series with the oil pump 39 and the stationary capillary tube 42, there is no delay in achieving constant oil pressure as would be occasioned by the usual bypass control. The use of an oil pump having an Archimedes screw 46 maintains the oil at substantially the same temperature as the oil in the reservoir so that the viscosity of the oil remains constant. The needle valve 50 provides a fine adjustment so that just the right amount of oil can be supplied to the raceway 26 of the loop taker.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth the nature of the invention, what is claimed herein is:

1. A lubricating system for a sewing machine having a frame, an oil reservoir in said frame, a rotating shaft having an axial bore mounted in said frame, a loop taker connected to the rotating shaft, said loop taker including a CFI stationary member having a bearing surface and a rotary member having a bearing surface mating with the bearing surface of the stationary member and a conduit communicating with the axial bore in the rotating shaft and extending to the bearing surface of the rotary member for transmitting oil to said bearing surface, said lubricating system comprising a stationary capillary tube for oil mounted in the bore in the rotating shaft and communicating with the conduit in the rotary member of the loop taker, means connected to the capillary tube to retain the capillary tube against rotation, means for supplying oil to the capillary tube from the reservoir in the sewing machine frame and ultimately to the bearing surface of the rotary member at substantially the same temperature as the oil in the reservoir, and a valve in the lubricating systern which is formed by said means for supplying oil to the capillary tube, said capillary tube and said conduit in the rotary member 0f the loop taker.

2. The'lubricating system of claim 1 in which the means for supplying oil to the capillary tube is an oil pump having an Archimedes screw.

3. A lubricating system for a sewing machine having a frame, an oil reservoir in said frame, a rotating shaft having an axial bore mounted in said frame, a loop taker connected to the rotating shaft, said loop taker including a stationary member having a bearing surface and a rotary member having a bearing surface mating with the bearing surface of the stationary member and a conduit communicating with the axial bore in the rotating shaft and extending to the bearing surface of the rotary member for transmitting oil to said bearing surface, said lubricating system comprising a bearing tube having an axial bore mounted in the bore in the rotating shaft for rotation with the shaft, a stationary capillary tube for oil mounted in the bore in the bearing tube and communicating with the conduit in the rotary member of the loop taker, means connected to the capillary tube to retain the capillary tube against rotation, means for supplying oil to the capillary tube from the reservoir in the sewing machine frame and ultimately to the bearing surface of the rotary member at substantially the same temperature as the oil in the reservoir, and a manually adjustable valve in the lubricating system which is formed by said means for supplying oil to the capillary tube, said capillary tube and said conduit in the rotary member of the loop taker.

References Cited by the Examiner UNITED STATES PATENTS 2,383,152 8/1945 Parry 112-256 2,431,292 11/1947 Wood 112-256 2,441,942 5/1948 Van Ness 112-256 2,791,193 5/1957 Parry 112-256 JORDAN FRANKLIN, Primary Examiner.

G. H. KRIZMANICH, Assistant Examiner. 

